The program grant, "Interfacial Behavior of Biomaterials", has two objectives: 1) To develop a general theory for the interfacial behavior of biomaterials, and 2) To use the theory for solving a variety of clinically relevant biomaterials problems. Basic studies involving design, development, and characterization of biomaterials and the investigation of materials-metabolite interactions complement 13 applied science projects that are clinically important. The applied science projects involve material interfaces with hard and soft tissues, fluids, and metabolites, and with electrical interactions. The objectives of the project "Fixation of Joint Prostheses" are 1) To assess the feasibility of the use of bioglass coatings for permanent fixation of orthopaedic prostheses, and 2) To acquire information about the interactions between bioglass and synovial joint tissues. The animal model involves bioglass coated femoral head prostheses implanted in monkeys for six months. The implants and the surrounding tissues will be studied visually, with the scanning electron microscope, histologically, and subjected to mechanical tests to determine the quality of the fixation developed as well as the extent of the interactions between the bioglass coating and adjacent bone, cartilage, synovial membrane, and synovial fluid.